Heart problems are one of the leading causes of morbidity and mortality worldwide.
Ischemic heart disease and arrhythmias are the two major types of cardiac abnormalities with prevalence of 12% in the general population, manifested in a wide range of symptoms, most typically chest pain radiating to other parts of the body.
Chest pain is a common symptom occurring in many diseases other than heart disease and since acute ischemic or arrhythmic events can be fatal, a prompt differentiation of the pain's origin could save lives. Ascertaining the symptomatic cardiac origin of the patient's condition can, potentially, shorten the “time to medical consultation” and in turn shorten the “time interval to medical intervention”, thereby reducing morbidity and mortality. The indirect results of an accurate diagnosis of a person's condition may prove of great economical value (since an accurate diagnosis may mean fewer hospitalization days, fewer unnecessary trips to the emergency room and so on).
The traditional tool primarily used to detect cardiac events is the Electrocardiogram (ECG). The ECG is a popular tool mainly because it is noninvasive and supplies immediate results (although it also has two major downfalls manifested in its large size, high cost and complexity mainly attributed to the number of wires involved).
Conventionally, when an electrocardiogram of a patient is detected, measured, and recorded in a hospital or a like facility, a total of ten electrodes are attached to the body surface of the patient; namely, six positions for chest leads, and four positions for limb leads. Six limb-lead waveforms (I, II, III, aVR, aVL, and aVF) of standard 12-lead waveforms and six chest-lead waveforms (V1, V2, V3, V4, V5, and V6) of the same are derived from electric potentials of the heart detected and measured by the ten electrodes by measuring means. General measurement positions are shown in FIGS. 1A and 1B, depicting the position used to obtain a 12-lead electrocardiogram.
Such diagnosis and treatment using a plurality of electrodes is possible in a fully-equipped hospital, or the like. However, in an at-home situation it has to date not been possible to obtain a 12 lead ECG using a small device comprising a minimal number of mobile and cordless electrodes, which is easy to use and which will enable detection of heart attack, any time, anywhere and in a low cost.
Mobile ECG units using handheld devices (such as a mobile phone) and telemedicine have been described in the art; however, they collectively do not provide an accurate home use device that could be simply and accurately used by any individual with no need of a prior medical knowledge.
For example US application NO. US2006224071 describes a method off inferring 12 lead ECG from reduced number of electrodes. The electrodes are located at V2 and V5 locations plus at least one electrode positioned substantially level with V5 on the right anterior auxiliary line, and at least one further electrode positioned on each of the right hand side and left hand side of the body. Although requiring a reduced number of electrodes in order to monitor 12 lead ECG, this method does require at least 5 electrodes including one in a non-conventional recording location.
Similarly, PCT Publication WO 2004/038942 to LEE describes a 4 wired electrode recording using a mobile telephone battery pack to detect an ECG. However the application does not indicate which electrode locations are used and does not teach that a full 12 lead ECG may be inferred from the recordings. The electrodes are adhesive, fixed and must be placed in the correct position in order to achieve an accurate reading. In addition, the data is first transmitted to the telephone's battery pack and from there to the telephone itself. Finally, the method described in the above publications requires modifications in the telephone's hardware and software.
US Application Publication No. US2006025695 to WEI describes a method for deriving a 12 lead ECG using a conversion matrix that allows the use of a smaller number of electrodes to predict a 12 lead ECG. However the described device uses 5 electrodes to obtain the 12 lead ECG recording. Furthermore, WEI does not describe a wireless or mobile device that is able to analyze and decipher a 12 lead ECG accurately.
European patent number EP1188412 to Brodnick et al describes an ECG monitor connected to a plurality of lead wires, each lead wire having a transducer capable of receiving an ECG signal from a patient, the ECG monitor having a processor to process the ECG signals from the plurality of lead wires and produce ECG data representative of cardiac condition of the patient, with a wireless communication interface coupled to receive patient ECG data from the ECG monitor and to transmit patient ECG data to a health care provider. Again the issue of mobility is not addressed by Brodnick et al.
German patent number DE10048746 to Tuncay is a device for the receipt and conversion of ECG-signals with three electrodes which are applied to the upper torso of the patient and which are connected via a cable to an A/D converter; however the taught method does not produce a 12 lead ECG which is sufficiently accurate for diagnosis.
German patent number DE19707681 to Erbel et al. relates to a mobile telephone comprising a housing, a transmitter, at least one receiver, a call number memory and buttons located on the housing. The taught device is configured in such a way that at least one emergency call button is mounted on the housing. However it does not teach or suggest obtaining a specific ECG configuration.